GB2382275A

GB2382275A - Transmitting/receiving information about orthogonal variable spreading factor codes assigned to user data in a data packet access communication system

Info

Publication number: GB2382275A
Application number: GB0218506A
Authority: GB
Inventors: Sung-Hoon Kim; Hyun-Woo Lee; Kook-Heui Lee; Ju-Ho Lee; Sung-Ho Choi
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2001-08-11
Filing date: 2002-08-09
Publication date: 2003-05-21
Anticipated expiration: 2022-08-09
Also published as: DE10236913A1; SE0202405D0; JP2003143108A; FI20021460A0; GB0218506D0; CA2397428A1; CN1331364C; KR100446509B1; US20030108025A1; CN1426247A; SE522538C2; US7164650B2; GB2382275B; AU2002300503B2; SE0202405L; DE10236913B4; FR2828606B1; FI20021460A; ITMI20021821A1; FR2828606A1

Abstract

A method of transmitting and receiving information about successive orthogonal codes assigned to user data for spreading on a control channel before transmission of the user data on a plurality of code channels in an HSDPA (High Speed Data Packet Access) communication system. A Node B determines an offset between a starting orthogonal code among the assigned orthogonal codes and the first of a plurality of successive orthogonal codes available to the HSDPA communication system, determines the number of the assigned orthogonal codes counted from the staffing orthogonal code being the number of the code channels, forms orthogonal code information indicating the offset and the number of the orthogonal codes, and transmits the orthogonal code information to a UE. A logical indicator corresponding to the orthogonal code information is transmitted to the UE which stores a table of logical indicators and corresponding orthogonal code information.

Description

METHOD FOR TRANSMITTING/RECEIVING INFORMATION ABOUT

ORTHOGONAL VARIABLE SPREADING FACTOR CODES ASSIGNED

TO USER DATA IN A HIGH SPEED DATA PACIFIST ACCESS

COMI ICATION SYSTEM

PRIORrFY This application claims priority from an application entitled "Method of Transmitting/Receiving Information about Orthogonal Variable Spreading Factor 10 Codes Assigned to User Data in High Speed Data Packet Access Communication System" filed in the Korean Industrial Property Office OD August 11, 2001 and assigned Serial No. 2001-48580, the contents of which are hereby incorporated by reference.

15 BACKGROUND OF al Aid INVENTION

1. Field of the Invention

The present invention relates generally to an HSDPA (High Speed Data Packet Access) communication system, and in particular, to a method of -a Is 20 transmitting/receiving information about OVSF (Orthogonal Variable Spreading Factor) codes assigned to user data.

2. Description of the Related Art

HSDPA is a generic term that refers to data transmission schemes that 25 bring high-speed data delivery to terminals by means of the HS-DSCH (High Speed-Downlink Shared Channel) and its related control channels in UMTS (Universal Mobile TelecoTrununications System). To support HSDPA, AMC (Adaptive Modulation and Coding) scheme, HARQ (Hybrid Automatic Retransmission Request) scheme, and FCS (Fast Cell Selection) have been

proposed. A. AMC(Adaptive Modulation and Coding) AMC is a scheme for adapting the modulation and coding format based on a received signal quality of a UE (IJser Equipment) and a channel condition between a particular Node B and the UE to increase a use efficiency of an entire cell. Therefore, the AMC scheme involves a plurality of MCSs(modulation and coding schemes). The MCSs can be defined from level 1 to level n. In other ? lo words, the AMC scheme is an adaptive selection of an MCS level according to the channel condition between the UE and the serving Node B. B. FCS (Fast Cell Selection) 15 When the UE enters a soft handover region, it selects the cell that is best able to transmit the required data. When a {JE supporting HSDPA enters a soft handover region defined as the overlapped region of a first Node B and a second Node B. it establishes radio links with the Node Bs. The cells of the Node Bs that have radio links with the UE are the active set of the UK. Data delivery from only 20 the best cell in a channel condition in the active set is FCS. Here, the best cell is a cell that has the best channel condition among the cells in He active set. The UE periodically monitors the channel conditions with the cells in the active set to check whether there is a cell better than the present best cell. If such a cell is detected, the UE transmits a Best Cell Indicator (BCI) to the cells in the active 25 set to change the best cell. The BCI contains the identification (ID) of the new best cell. Upon receipt of the BCI, the cells determine whether the BCI indicates them. Then, the new best cell transmits an HSDPA packet to the UE on an HS DSCH, thus reducing the overall interference.

C. e-channel SAW HARQ (e-channel Stop And Wait Hybrid Automatic Retransmission Request! scheme Two schemes are introduced to increase typical ARQ (Automatic 5 Retransmission Request) efficiency. That is, a retransmission request and a response for the retransmission request are exchanged between a UE and a Node B. and defective data is temporarily stored and combined with corresponding retransmitted data. e-channel SAW HARQ scheme has been introduced to HSDPA to make up for the weak points in the conventional SAW ARQ scheme.

-? Io In the SAW ARQ scheme, the next packet data is not transmitted until an ACK (Acknowledgement) signal for the previous transmitted packet data is received.

Thus although the packet data can be transmitted, it is delayed to await the ACK signal. On the other hand, packet data can be successively transmitted without receiving the ACK signal for the previous packet data in the e-channel SAW 15 HARQ, thereby increasing the use efficiency of channels. If n logical channels are established between a UE and a Node B. and identified by time or channel numbers, the UK, upon receipt of packet data at a certain timing point, can determine the logical channel that transmitted the packet data. Thus the UE can rearrange packet data in the right reception order or soD-combine the packet data.

A plurality of UEs share part of downlink transmission resources in an HSDPA communication system. The downlink transmission resources include transmission power and OVSF codes. Use of 10 OVSF codes when SF (Spreading Factor)=16 and use of 20 OVSF codes when SF=32 in the HSDPA 25 communication system are under discussion.

A plurality of UEs can share a plurality of available OVSF codes at the same time, that is, which implies that OVSF code multiplexing is possible for the UEs at a certain time in the HSDPA communication system. OVSF code

multiplexing will be described with reference to FIG. 1.

FIG. 1 illustrates an example of OVSF code assignment in a typical HSDPA communication system when SF=16. Referring to FIG. 1, each OVSF 5 code is expressed as C(i, j) according to its position in a code tree. In C(i, j), the variable i indicates the SF and the variable j is a sequence number indicating the position of the OVSF code from the lef anost end of the code tree. For example, C(16, 0) represents the first OVSF code with SF=16 counted from the left in the code tree. As illustrated, the 7th to 16 OVSF codes with SF=16, that is, 10 10 OVSF codes C(16, 6) to C(16, 15) are assigned. The 10 OVSF codes can be multiplexed for a plurality of UEs as illustrated in Table 1.

(Table 1)

Time UE tO tl _ C(16, 6 - C(16, 7) C'16, 6) C(16, 8) C(16, 6) C(16, 10)

B C(16, 8) C(16, 10) C(16, 9} C(16, 10) C(16, ll) C(16, 14) _. _ C C(16, ll) C(16, 15) C(16, ll) C(16, 15) C(16, 15) 15 In Table 1, UEs A, B. and C perform code multiplexing on their <-hi respective assigned OVSF codes at timing points to, tl, and t2. A Node B determines the number of OVSF codes and their positions in the code tree to be assigned to each UE according to tile amount of user data for the each UE and the channel condition between the Node B and the each UK.

It has been proposed that the OVSF code information is delivered to each UE on a downlink control channel in the HSDPA communication system. First a channel structure in the HSDPA communication system will be described.

25 The HSDPA communication system has an HS-DSCH for transmitting downlink user data, a downlink control channel, and an uplink control channel.

The HS-DSCH transmits the UEs user data using the OVSF codes assigned to the HSDPA communication system. To support an AMC scheme, a HARQ scheme, and an FCS scheme, control information must be exchanged between the Node B and the UEs via the downlink and upIink control channels.

s The uplink control channel transmits a periodical CQI (Channel Quality Information), ACK (Acknowledgement)/NACK (Negative ACK) signals indicating whether received user data has an error or not, and a best cell information. The downlink control channel transmits a particular UE an HI (HS 3 10 DSCH Indicator) indicating that the UE will receive user data on the HS-DSCH, an MCS level to be used for the data transmission, and information about OVSP codes to be assigned.

FIG. 2 is a block diagram of a transmitter for transmitting information 15 about OVSF codes assigned to user data in the typical HSDPA communication system. Referring to FIG. 2, the transmitter takes charge of user data transmission on the HS-DSCH and control information transmission on the downlink control channel in a Node B of the HSDPA communication system.

The transmitter includes an AMC controller 201, a scheduler 202, a transmission 20 buffer 203, a turbo encoder 204, a user data transmitter 205, a control information generator 206, a channel encoder 207, and a control data transmitter 208. The transmission buffer 203 buffers user data received from a higher layer and outputs the user data to the turbo encoder 204 under the control of the scheduler 202. The turbo encoder 204 turbo-encodes the user data under the 25 control of the AMC controller 201. The AMC controller 201 determines an MCS level for the user data according to the channel condition between the Node B and a UK, and controls the turbo encoder 204 to encode the user data according to the MCS level. The user data transmitter 205 modulates the encoded user data according to the MCS level, channelizes the modulated data, and transmits the

user data to the UK.

The scheduler 202 controls information about OVSF codes used for the channelization and determines a user data transmission time and OVSF codes to 5 be used for the UK, taking into account the amount and types of user data for other UEs.

The control information generator 206 converts information about the determined MCS level received from the AMC controller 201 and the OVSF 10 code information received from the scheduler 202 to a format suitable for a radio channel. If the control information is to be transmitted on a DPCCH (Dedicated Physical Control Channel), the control information generator 206 converts the control information to a DPCCH transmit format. The channel encoder 207 channel-encodes the control information received from the control information 15 generator 206 with a channel encoding scheme. Here, tile channel encoding scheme is convolutional coding or turbo coding. The control data transmitter 208 performs modulation and channelization on the encoded control information and transmits the control infonnation to the UP on a radio link.

20 FIG. 3 is a block diagram of a receiver for receiving OVSF code information in the typical HSDPA communication system. Referring to FIG. 3, the receiver receives user data on the HS-DSCH and control information on a downlink control channel in the UK. The receiver is comprised of a control data receiver 301, a channel decoder 302, a control information interpreter 303, a user 25 data receiver 304, a turbo decoder 305, and a reception buffer 306.

Upon receipt of data on a radio link, the data is fed to the control data receiver 301 and the user data receiver 304. The radio link is a channel predetermined between the Node B and the UE for transmitting downlink control

information, for example, a DPCCH. The control data receiver 301 despreads and demodulates the received data.

The channel decoder 302 channel-decodes the signal received from the 5 control data receiver 301 in correspondence to the channel encoding scheme used in the transmitter. The control information interpreter 303 interprets MCS level information and OVSF code information from the control data received from the channel decoder 302. The MCS level information is output to the user data receiver 304 and the turbo decoder 305, and the OVSF code information is 3 10 output to the user data receiver 304.

The user data receiver 304 despreads and demodulates the received data using the OVSF code information and the MCS level information.

15 The turbo decoder 305 turbo-decodes the signal received from the user data receiver 304 in correspondence to the turbo coding scheme used in the transmitter using the MCS level information. The reception buffer 306 buffers the turbo-decoded signal and delivers He buffered user data to a higher layer at a particular timing point under a predetermined control. Thus, the receiver receives 20 user data from the Node B on the radio link using the OVSF code and MCS level information. As described above, the transmitter must transmit infonnation about OVSF codes assigned to user data so that the receiver can detect the user data 25 using He OVSF code information in the HSDPA communication system.

Therefore, an efficient way of transmitting OVSF code information so Mat Me first OVSF code and the number of OVSF codes to be assigned to user data are notified to the UE is under consideration.

Taking the situation specified by Table 1 as an example, in order to transmit user data to a UE A using OVSF codes C(16, 5) and C(16, 6) at time to, information about the OVSF codes must be transmitted to the UE A earlier than time t0. The OVSF code information may be constructed as illustrated in Table 2.

(Table 2)

Time UE _ A C(16, 6 C(16, 7) C(16, 6) C(16, 8) C(16, 6) C(16, 10)

SP: 0110 SP: 0110 SP: 0110

NC: 0010 NC. OOll NC: 0100 B C(16, 8) C(16, 10) C(16, 9) C(16, 10) C(16, 11) C(16, 14)

SP: 1000 SP: 1001 SP: 1011

NC: 0011 NC: OOIO NC: 0100

C C(16, 11) C(16, 15) C(16, 11) C(16, 15) C(16, 15)

SP: 1011 SP: 1011 SP: 1111

NC: 0101 NC: OlOO NC: 0001 In Table 2, SP (Start Point) represents a starting point of OVSF code assigned to user data in an OVSF code tree. The left most OVSF code is 10 expressed as 0000 and the right most OVSF code is expressed as 1111. NC : (Number of Code) is the number of OVSF codes assigned to He user data, a_, expressed as a binary number. When 10 OVSF codes with SF=16 are assigned to an HSDPA communication system, expression of the SP requires 4 bits and expression of the NC requires 4 bits.. Thus OVSF code information is delivered 15 in the remaining 8 bits.

To generalize the expression of the OVSF code information, the number of bits for representing the SP is R(log2n) when NH OVSF (Number of Codes for HSDPA) codes with SF=n are assigned to the HSDPA communication system.

20 Here, it(x) is art integer equal to or greater than a real number x. If a plurality of

OVSF codes are assigned to a UK, the OVSF codes are assumed to be successive on the OVSF code tree.

The OVSF code information expressed as the SP and NC is part of the 5 control information that was described referring to FIGs. 2 and 3 as being transmitted from the Node B to the UE via the radio link. Since the OVSF code information is transmitted to the UE on a downlink control channel, for example, a DPCCH, each time user data is transmitted on the HS-DSCH, it is preferable to minimize the size of the OVSF code information. However, the OVSF code - 10 information expressed as an SP and an NC requires more bits than are actually needed. SUMMARY OF THE INVENTION

15 Embodiments of the present invention seek to provide a method of transmitting/receiving information about OVSE codes assigned to user data in an HSDPA communication system.

Embodiments of the present invention also seek to provide a method of -) 20 transmitting/receiving information about an offset and a number of OVSF codes assigned to user data as OVSE code information.

Accordingly, a Node B determines an offset between a starting orthogonal code among assigned successive orthogonal codes and a first of a 25 plurality of successive orthogonal codes available to an HSDPA communication system, determines a number of the assigned orthogonal codes counted from the stardng orthogonal code being a number of the code channels, forms orthogonal code information indicating the offset and the number of the orthogonal codes, and transmits the orthogonal code information to a UK.

g

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present 5 invention will become more apparent from the following detailed exemplary description when taken in conjunction with the accompanying drawings in

which: FIG. 1 illustrates an example of OVSF code assignment to a typical HSDPA communication system; 10 FIG. 2 is a block diagram of a transmitter for transmitting information about OVSF codes assigned to user data in the typical HSDPA communication system; FIG. 3 is a block diagram of a receiver for receiving the OVSF code information in the typical HSDPA communication system; 15 FIG. 4 is a block diagram of a transmitter for transmitting information about OVSF codes assigned to user data in an HSDPA communication system according to an embodiment of the present invention; and FIG. 5 is a block diagram of a receiver for receiving the OVSF code information in the HSDPA communication system according to the embodiment ,. 20 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of He present invention will be described herein 25 below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail

since they would obscure the invention in unnecessary detail.

In the present invention, OVSF code information to be transmitted from

a Node B to a UE in an HSDPA communication system is generated for each available OVSF code assignment for a UK. When an OVSF code assignment is determined for the UK, corresponding OVSF code information including the offset and the number of assigned OVSF codes is transmitted to the UK. Here, 5 the offset is the stating point of OVSF code assigned to user data for the UE in a OVSF code tree.

Generation of the OVSF code information with the available OVSF code assignment considered will be described on the assumption that 10 OVSF codes 10 with SF=16 (that is, the 7th to 16th OVSF codes), for example, C(16,6) to C(16,15), are assigned to the HSDPA communication system. All available OVSF code assignments for the UE are listed in Table 3.

(Table 3)

Number of OVSF Number of possible OVSF codes l codes cases. | 10 1 - 1 [C(16,6) C(16,15)]

9 2 [C(16,6 -C(16,14)], [C(16,7 C(16,15)]

- _ _

8 3 [C(16, 6 C(16, 13)], [C(16, 7)-C(16, 14)], [C(16,

8)-C(16, 15)]

. 4. _ [C(16, 6 -C-(16, 12)], [C(16, 7} C(16,13)], [C(16,

8 C(16, 14)], [C(16,9 -C(16,15)]

_.._ 6 5 [C(16, 63 C(16, 11)], [C(16, 7 -C(16, 12)], [C(16,

8 -C(16, 13)], [C(16, 9)-C(16, 14)], [C(16,

10 -C(16, 15)]

_. 5 _6 [C(16,6) C(16,10)],..., [C(16, ll) C(16,15)] 4 7 [C(16,6 -C(16,9)] ,..., [C(16,12 -C(16,15)]

_ _ 3 18 1 [C(16,6 -C(16,8)],..., [C(16,13 -C(16,15)]

2 9 [C(16,6), C(16,7)],..., [C(16,14) C(16,15)]

1- 1 -10 - I [C(16,6)],..., [C(16, 15)]

Referring to Table 3, when the number (NU) of OVSF codes assigned to the UE is equal to the number (NH) of all OVSF codes available in the HSDPA communication system, the number of possible cases is 1. When NU is less than NH by 1, that is, NU is 9, the number of possible cases is 2, that is, [C(16, 5 6) C(16, 14)] or [C(16, 7) C(16, 15)] are assigned to the UK. If NU is 8, the number of possible cases is 3.

Therefore, the total number of codes (TNC) of all possible cases for the UE in the HSDPA communication system is calculated by -) 10 ho 77VC = z +1 NU-] (1) Then, the number of bits required to express OVSF code information is 1 5 R0og2 C).

Comparisons between the number of bits required to express the conventional OVSF code information and the number of bits required to express --hi the OVSF code information in the present invention are illustrated in Table 4.

(Table 4)

Number of bits for Number of bits for inventive conventional OVSF code OVSF code information information SF= 16, NH- 10 R(logz 1 6)+R(log: 10)=8 R(log25 5)=6 SF=32, NH=20 R(log:32)+R(log:20)= 10 R(log:2 10)=8 SF=64, NH=40 R(log:64)+R(log:40)=12 R(log2820)= 10 As noted from Table 4, the OVSF code information of the present

invention can be transmitted in fewer bits than the conventional OVSF code information. While the OVSF code information is formed independently to indicate the SP and NC of an OVSF code assignment in the conventional technology, the OVSF code information is generated for each of all possible 5 OVSF code assignments for a UE and stored in a table, and when particular OVSF codes are assigned to the UK, a logical indicator corresponding to the OVSF code information in the table is transmitted to the UE in the present invention. The procedure of fanning the OVSP code information corresponding to each OVSF code assignment is performed in a known manner and thus its - 10 description is avoided here. The logical indicator indicates the offset and number

of assigned OVSF codes.

The OVSF code information of all possible cases can be mapped to logical indicators in many ways. For example, OVSF code information for the 15 case where NU=NU is set to be 0 and then OVSF code information for each of the other cases is set to be increased by 1 from the previous OVSF code information, or vice versa.

Table 5 illustrates OVSF code information mapping to logical indicators 20 when the 7 to 16 OVSF codes with SF=16 in the code tree, that is, C(16, 6) to C(16, 15) are assigned to the HSDPA communication system.

(Table 5)

SP NC Logical 1 SP 1 NC l Logical _ indicator 1 indicator C(16,6) - lo 1 000000 1 C(16,6) 3 1 011100 C(1 6,6) 9 00000 1 C( 1 6,7) 3 01 1 1 0 1

C(16,7) 9 1 000010 C(16,8) _ 011110

C(16,6) 8 000011 C(16,9) 3 011111

C(16,7) 8 000100 C(16,10) 1 100000-

C(16,8) 8- I 000101 C(16,11)... 100001

_

C(16,6) 7 000110_ C(16,i2) 3 100010 -

C(16,7) 7 000111C(16,13) 3 100011

C(16,8) 001000C(16,6) 100100

C(16,9) 7 001001C(16,7). 2 100101

C(16,6) 6__ 001010C(16,8) 2 100110

- C(16,7) 6 001011C(16,9) 2 100111

- C(16,8) 6 001100C(16,10) 2 101000

C(16,9) 6 001101C(16,11) 2 101001

C(16,10) 001110C(16,12) 101010

C(16,10.5 001111C(16,13) 101011

C(16,7) 5 010000C(16,14) _ 2 101100

C(16,8)_ 5 010001C(16,6) 1 101101

C(16,9) 5 010010C(16,7) 1 101110

C(16,10) 5- 010011- C(16,8j 1 lOlli] - C(16,11) 5_ 010100 _ C(16,9) 1 110000

C(16,6) 010101 C(16,10) 1 110001

C(16,7) - 4 010110 C(16,11) 110010

C(16,8) 010111 C(16,12) 110011

C(16,9) 4 011000 C(16,13) 1 110100

C(16,10) 011001 C(16,14) 1 110101

C(16,11) 4 011010 C(16,15) 1 110110

C(16,12) 4 011011

The above OVSF code information table may be generated by the Node B. or a higher layer, for example, a RNC (Radio Network Controller).

Now a description will be made of a transmitter and a receiver for

transmitting and receiving OVSF code information using the OVSF code information table in He HSDPA communication system with reference to FIGs. 4 and 5.

10 FIG. 4 is a block diagram of a transmitter for transmitting information about OVSF codes assigned to user data in an HSDPA communication system according to an embodiment of the present invention. In FIG. 4, the transmitter

transmits user data on the HS-DSCH and control information on the downlink control channel in a Node B of the HSDPA communication system. The transmitter is comprised of an AMC controller 401, a scheduler 402, a transmission buffer 403, a turbo encoder 404, a user data transmitter 405, a 5 control information generator 406, a channel encoder 407, a control data transmitter 408, and an OVSE code information table 409.

The transmission buffer 403 buffers user data generated in a higher layer and outputs the user data to He turbo encoder 404 under the control of the 10 scheduler 402. The turbo encoder 404 turbo-encodes the user data under the control of the AMC controller 401. The user data transmitter 405 modulates the turbo-encoded signal according to an MCS level received from the AMC controller 401, channelizes the modulated signal according to OVSF code information received from the scheduler 402, and transmits the resulting signal to 15 a corresponding UE on a radio link. The AMC controller 401 determines the MCS level and modulation scheme suitable for the UE based on control information received from the UK.

The scheduler 402 determines the transmission time and OVSF codes of - 3 20 the user data for the UK, taking into account the amount and types of user data for other UEs supporting HSDPA. Then the scheduler 402 searches for a logical indicator corresponding to the OVSF code assignment in the OVSF code information table 409 and outputs the logical indicator to the control information generator 406. The AMC controller 401 also feeds the MCS level information to 25 the control information generator 406.

The control information generator 406 converts the MCS level information and the logical indicator in a format suitable for a radio channel. For example, if a DPCCH transmits the control information, the control information

generator 406 converts the control information in the transmit format of the DPCCH. The channel encoder 407 channel-encodes the control information received from the control information generator 406 by a channel encoding scheme, for example, a convolutional coding scheme or a turbo coding scheme.

5 The control data transmitter 408 performs modulation and channelization on the channel-encoded control information and transmits the resulting control information to the UE on the radio link.

FIG. 5 is a block diagram of a receiver for receiving the OVSF code 10 information in the HSDPA communication system according to the embodiment of the present invention. In FIG. 5, the receiver receives user data on the HS-

DSCH and control information on a downlink control channel in the UE in correspondence to the channel encoding scheme used in Me transmitter. The receiver is comprised of a control data receiver 501, a channel decoder 502, a 15 control information interpreter 503, a user data receiver 504, a turbo decoder 505, a reception buffer 506, and an OVSF code information table 507.

Upon receipt of data on a radio link, the data is fed to the control data receiver 501 and the user data receiver 504. The radio link is a channel 20 predetermined between the Node B and the UE for transmitting downlink control information, for example, a DPCCH. The control data receiver 501 despreads and demodulates the data.

The channel decoder 502 channel-decodes the signal received from the 25 control data receiver 501. The control information interpreter 503 interprets MCS level information and OVSF code information from the control data received from the channel decoder 502. The MCS level information is output to the user data receiver 504 and the turbo decoder 505, and the OVSF code information is output to the user data receiver 504.

To interpret the OVSF code information, the control information interpreter 503 detects a logical indicator representing the OVSF code information from the received control data, searches for the OVSF code 5 infonnation indicative of an offset and an NC in correspondence with the logical indicator in the OVSF code information table 507, and outputs the OVSF code information to the user data receiver 504. Using the MCS level information and the OVSF code information, the UE receives user data from the Node B on the radio link.

The user data receiver 504 despreads and demodulates the received data using the OVSF code information and the MCS level information. The turbo decoder 505 turbo-decodes the signal received from the user data receiver 504 in correspondence to the turbo encoding scheme used in the transmitter using the 15 MCS level information. The reception buffer 506 buffers the turbo-decoded signal and delivers the buffered user data to a higher layer at a particular time under predetermined control.

Meanwhile, it has described by a way of example hereinbefore, that the ) 20 OVSF code information is mapped to a logical indicator in consideration of all possible cases such as information about an offset and a number of code. In this regard, it should be understood that there are other possible methods for transmitting OVSF code infonnation after mapping to the logical indicator. That is, as stated above, the OVSF code information can be mapped to the logical 25 indicator in consideration of all possible cases. Also, it is possible to map the OVSF code information by the minimum number of bits in combination with the information about an offset and a number of code. For example, the OVSF code information can be expressed by assigning a first number of bits, for example 3 bits, to carry the information about the number of code and by assigning a second

number of bit, for example 4 bits, to carry the information about the offset. When the OVSF code information is determined by respectivelyassigning the first and second number of bits in order to express the OVSF code information, if the entire number of assignable OVSF code is changed in a HSDPA communication 5 system, i.e., is increased, the information about the number of code is expressed as the second number of bits and the information about offset is expressed as the first number of bits. That is, the information about offset or the number of code can consist of He number of bits expressible as the maximum number of assignable OVSE code in a HSDPA communication system. In addition, any one - 10 of the offset information and information about the number of code is determined by the first number of bit, for example 4 bits which represents the maximum number of assignable OVSF code in the HSDPA communication system. The other is determined by the second number of bit, for example 3 bits which is 1 bit smaller than the first number of bit. Therefore, as stated above, it is clearly 15 shown that the objective of the present invention is that OVSF code information to be assigned consists of the optimal number of bits using the information about the offset and the number of code and transmitted in the HSDPA communication system. ) 20 In accordance with the present invention as described above, OVSF code information is formed to indicate the offset and the number of assigned OVSF codes in each of all possible cases of OVSF code assignment and mapped to logical indicators in a table in an HSDPA communication system. Referring to the OVSF code information table, OVSF code information corresponding to an 25 OVSF code assigurnent for a UE is transmitted to the UE as a corresponding logical indicator. The thus- formed OVSF code information requires a smaller number of bits than in the conventional OVSF code information. Therefore, both He efficiency of the information transmission/reception and resource efficiency are increased.

While We invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without 5 departing from the scope of the invention as defined by the appended claims.

The preferred features of the invention are applicable to all aspects of the invention and may be used in any possible combination.

10 Throughout Me description and claims of this specification, the

words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other components, integers, moieties, additives or steps.

-

Claims

WHAT IS CLAI1VIED IS:

1. A method of transmitting infonnation about successive orthogonal codes assigned to user data for spreading on a control channel before 5 transmitting the user data on a plurality of code channels to a UE (User Equipment) in a Node B of an HSDPA (High Speed Data Packet Access) communication system, the method comprising the steps of: determining an offset between a starting orthogonal code among a assigned orthogonal codes and a first of a plurality of successive orthogonal 3lo codes available to the HSDPA communication system; determining a number of the assigned orthogonal codes counted from the starting orthogonal code being a number of the plurality of code channels; and forming orthogonal code information indicating the offset and the number of the orthogonal codes and transmitting the orthogonal code information 15 to the UK.

2. The method of claim 1, wherein the orthogonal code information is mapped to one of a plurality of logical indicators predetermined between the UE and the Node B. -A20

3. The method of claim 2, wherein each of the plurality of logical indicators is mapped to one of a plurality of pieces of orthogonal code information generated for each possible case of orthogonal code assignment.

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4. The method of claim 1, wherein the orthogonal codes are OVSF (Orthogonal Variable Spreading Factor) codes.

5. A method of assigning orthogonal codes for an HSDPA (High Speed Data Packet Access) communication system having a maximum number

of available orthogonal codes, the method comprising the steps of: determining an offset indicating a difference between a first orthogonal code and a starting orthogonal code, wherein the starting orthogonal code is a first orthogonal code among a plurality of assigned orthogonal codes; 5 determining a number of orthogonal codes being assigned from the starting orthogonal code; and transmitting orthogonal code information including the offset and the number of the assigned orthogonal codes to a UK.

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6. The method of claim 5, wherein at least one of the offset and the number of orthogonal codes consists of a number of bits indicating an entire number of codes used for HSDPA.

7. The method of claim 5, wherein one of the offset and the number 15 of orthogonal codes consists of a first number of bit indicating a maximum number of bit and the other consists of a second number of bit which is 1 bit smaller than the first number of bit.

8. A method of receiving information about orthogonal codes ) 20 assigned to user data for spreading on a control channel from a Node B before An.. the user data is received from the Node B on a plurality of code channels in a UE (User Equipment) of an HSDPA (High Speed Data Packet Access) communication system, the method comprising the steps of: Respreading a predetermined received channel signal; 25 detecting orthogonal code information of the user data from the despread channel signal; and detecting an offset between a starting orthogonal code among a plurality of assigned successive orthogonal codes and a first of a plurality of successive orthogonal codes available to the HSDPA communication system and a number

of the orthogonal codes being number of the code channels from the orthogonal code information.

9. The method of claim 8, wherein the orthogonal code information 5 is mapped to one of a plurality of logical indicators predetermined between the UE and the Node B.

10. The method of claim 9, wherein each of the plurality of logical indicators is mapped to one= of a plurality of pieces of orthogonal code - 10 information generated for each possible case of orthogonal code assignment.

I 1. The method of claim 8, wherein the orthogonal codes are OVSF (Orthogonal Variable Spreading Factor) codes.

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12. A method of transmitting and receiving information about successive orthogonal codes assigned to user data for spreading before the user data is transmitted and received on a plurality of code channels in an HSDPA (High Speed Data Packet Access) communication system, the method comprising the steps of: ) 20 forming orthogonal code information indicating an offset between a starting orthogonal code among the assigned orthogonal codes and a first of a plurality of successive orthogonal codes available to the HSDPA communication system and a number of the assigned orthogonal codes counted from the starting orthogonal code being a number of the plurality of code channels by a Node B; 25 transrniffing the orthogonal code information to a UE (User Equipment) on a predetermined channel by the Node B; receiving the predetermined channel and detecting the orthogonal code information from the channel signal by the UK; and detecting the offset and the number of the orthogonal codes from He

orthogonal code infonnation by the UK.

13. The method of claim 12, wherein the orthogonal code information is mapped to one of a plurality of logical indicators predetermined 5 between the UE and the Node B.

14. The method of claim 13, wherein each of the plurality of logical indicators is mapped to one of a plurality of pieces of orthogonal code infonnation generated for each possible case of orthogonal code assignment.

15. The method of claim 12, wherein the orthogonal codes are OVSF (Orthogonal Variable Spreading Factor) codes.

16. A method of receiving information-about assigned orthogonal 15 codes for an HSDPA (High Speed Data Packet Access) communication system having a maximum number of available orthogonal codes, the method comprising the steps of: detecting an offset indicating a difference between a first orthogonal code and a starting orthogonal code, wherein the starting orthogonal - ' 20 code is a first orthogonal code among a plurality of assigned orthogonal codes; detecting a number of orthogonal codes being assigned from the starting orthogonal code; and receiving a user data on a predetermined channel using the assigned orthogonal codes.

17. The method of claim 16, wherein at least one of the offset and the number of orthogonal codes consists of a number of bits indicating an entire number of codes used for HSDPA.

18. The method of claim 16, wherein one of the offset and the number of orthogonal codes consists of a first number of bit indicating a maximum number of bit and the other consists of a second number of bit which is 1 bit smaller than the first number of bit.

19. A method of transmitting information, substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings. 10

20. A method of assigning orthogonal codes, substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.

21. A method of receiving information about orthogonal codes, 15 substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.

22. A method of transmitting and receiving information about successive orthogonal codes, substantially as hereinbefore described with 20 reference to Figures 4 and 5 of the accompanying drawings.

23. A method of receiving infonnation about assigned orthogonal codes, substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.